IRFP: Field Energetics and Diving Physiology of a Small Cetacean, the Harbor Porpoise

Mcdonald Birgitte I, La Jolla CA

Investigators

Abstract

The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad. This award will support a twenty-four-month research fellowship to Dr. Birgitte I. McDonald to work with Drs. Peter Madsen and Tobias Wang at Aarhus University in Aarhus, Denmark. Cetaceans (whales, dolphins and porpoises) are among the largest animals ever to evolve, and as apex predators in marine ecosystems, they have a significant top-down effect on prey targeted during long, deep breath-hold dives. It is therefore essential to understand the energetic requirements and oxygen management of cetaceans if we are to interpret and understand their role in the trophic energy cascades, their foraging ecology, limits of dive performance and ability to adapt to environmental change and disturbance. However, very little is known about the field physiology of cetaceans due their size and hostile habitats. Harbor porpoises are a unique model species to study the metabolic rates and diving physiology in a wild cetacean because of their small size and ability to be studied in captivity as well as in the wild This research addresses the above knowledge gaps by determining the energetic requirements and oxygen management strategy during diving in one of the smallest cetaceans, the harbor porpoise. The three main objectives are 1) Determining the field metabolic rate of harbor porpoises using a combination of field and laboratory studies, 2) Measuring heart rate in freely diving harbor porpoises, which for the first time document the level of bradycardia in a naturally diving cetacean. In addition, accelerometers will be used to determine workload/activity during dives. The relationship between heart rate and activity will be used to assess the potential level of muscle perfusion during dives with different activity levels, and 3) develop a self-contained biologger to measure blood flow and heart rate that can be used to measure cardiac output in freely diving marine mammals. The project provides important information on the metabolic requirements of a declining species that will aid in management and provides insight into the diving physiology of cetaceans. Further, it provides high level scientific training, fosters new domestic and international scientific collaborations, and offers expansive outreach activities including: 1) The training of the principle investigator in new research techniques and provides her with opportunities to teach and mentor graduate and undergraduate students. 2) The development and fostering of international and interdisciplinary collaborations. 3) Knowledge exchange between the principle investigator and the host institution. 4) The development of a blood flow data logger that can be used in a variety of diving animals to improve our understanding of oxygen management during diving. And 5) education outreach through the Fjord and Bælt Center (http://www.fjord-baelt.dk) about the importance of physiological research in understanding the ecology and biology of an organism and its role in the ecosystem.